This invention relates to multiple wire cables, and more particularly to small gauge coaxial wiring.
High speed data and signal transmission rates are limited by the characteristics of the conductors used for transmission. For electronic systems having separate components connected by a flexible multi-wire cable, the signal rate is limited not only by the nature of the flexible wires used for the cable, but by the means of connection between the cable and each component.
For high-rate applications, various high speed cabling may employed, including high performance coaxial wiring, twisted pair wires, or other configurations. Any selected cable has a given bandwidth or frequency capability, and may use Low Voltage Differential Signals (LVDS) to limit switching noise that may generate electromagnetic interference with other electronic functions. While cable bandwidth is a theoretical maximum, in practical application, bandwidth tends to be severely limited by the connections between cable and the circuit boards or other components normally used in the system components limit usable bandwidth. Discontinuities at junctions between different types of conductors can lead to reflections and ringing that require an extended time for clock cycles. Moreover, differences in transmission times for different lines may generate a skew, which also requires an extended period to encompass the range of times at which signals sent on each line arrive at their destination.
Normally, a connection between a cable and components requires a connector element at each end of the cable. Connectors have the facility to connect to the cable, as well as to a component such as a circuit board. Where the system requires detachability of cables and components, each end of the cable may include two mating connector components, one connected to the cable end, and the other connected to the circuit board. Such connectors each generate several discontinuities that limit bandwidth below the theoretical capabilities of the cable. Such discontinuities occur where a circuit board connects to one connector portion, where that connector portion mates with the corresponding other connector portion, and where that connects with the cable wires. The accumulated effect of these discontinuities is believed to reduce frequency bandwidth by about one half in some cases.
In addition to their effect on performance, conventional connectors add significantly to the cost and bulk of high speed cable systems. The connectors must be installed on the component boards, as well as on the cable, requiring skilled labor costs. Cable wire and circuitry components may be provided by different suppliers, each with a part of a necessarily mating connector, making compatibility a concern. In addition, a cable manufacturer may have customers specifying different connectors, requiring the stocking of different components. Manufacturing costs are also significant in that cables with a multitude of conductors must be carefully assembled to ensure that each conductor is connected to the proper contact on each connector.
The present invention overcomes the limitations of the prior art by providing a cable with a number of coaxial wires. Each of the wires has a central conductor encompassed by a dielectric sheath, and the sheath is encompassed by a conductive shield. The wires are arranged side-by-side in a row at an end of each wire, where a termination element is connected. The termination element has opposed major faces, with an array of first contacts on a first face, and an array of second contacts on the opposed face, each of the first contact being electrically connected to a corresponding second contact. Each of the central conductors of the wire elements is connected to a corresponding one of the first contacts. An electronic device may include circuit boards at each end, with contacts arranged for compressive contact with the second contacts. The termination element may be captured between a clamp and the board, with an elastomeric spring maintaining compression, and pinned holes in the termination element and board ensuring registration of the contacts.